The use of veins from donor animals, as replacements for diseased artery segments in other animals (venous allografts) will be studied. The immunological and biochemical response to this procedure will be characterized. Attempts to modify the graft prior to implantation will be carried out with the ultimate aim of developing vein banking procedures. The connective tissue response of injured vessels will be studied by characterizing the types of collagen produced. This is important in the understanding of vessel wound healing, thrombosis and atherosclerosis.